Cancer clinical trials are essential to translating research into tangible benefits for patients, but only a small number of patients enroll in a trial Under-enrollment of minorities is an even greater problem because it limits the generalizability of findings and contributes to treatment disparities. Minority under-enrollment in prostate cancer trials is especially troublesome because of the higher incidence, morbidity, and mortality of this cancer among African American men, as compared to White men. The overall goal of our research is to improve cancer care and reduce racial/ethnic cancer disparities by increasing rates at which African American men with prostate cancer make an informed decision to participate in a trial, based on high-quality communication with their physician. In this application, we propose a theory-based multilevel intervention designed to influence African-American patients' attitudes about physicians and about trials; physicians' attitudes about patients and about trials; and patient-provider clinical interactions in which trials may be discussed. The intervention is designed to improve these outcomes: patient understanding of trials and decisions to participate; physician decisions to discuss and offer trials; patient-physician communication; and ultimately, participation rates among African Americans with prostate cancer. We base the intervention on our prior research showing that patient and physician attitudes and beliefs often result in trials not being discussed during clinic visits, or when trials are discussed, communication is ineffective. These factors are even greater in racially discordant visits, and likely contribute to low trial enrollment among African Americans. We will conduct the proposed research at two NCI-designated comprehensive cancer centers that provide care in urban areas. African American and White men will be included to allow comparison of the effects of the intervention by patient race. The intervention has two phases. Phase 1 is a randomized trial in which intervention group patients receive a tool to improve their attitudes about trials and increase their active participation in clinic visits in which trials maybe discussed. Phase 2 is an interrupted time series quasi-experiment in which physicians receive an intervention to improve their attitudes about trials and their communication during discussions of trials with patients. Data will include patient and physician self-reports, video recordings of patient-physician clinic visits, and medical records. We propose three Specific Aims: 1) determine the independent and combined effects of each phase of the intervention on outcomes; 2) compare the effects of the intervention on outcomes for African American versus White men; and 3) examine the extent to which patient-physician communication mediates the relationship between the intervention and outcomes. This research is highly significant and innovative because it tests a new conceptual model focusing on patients, physicians, and clinical interactions, and uses social psychological and communication theory to improve clinical practice. Findings should provide evidence for a practical, exportable intervention to increase trial enrollment among African American men with prostate cancer.